title: Study of adrenergic, imidazoline, and endothelin receptors in clonidine-, morphine-, and oxycodone-induced changes in rat body temperature.
abstract: OBJECTIVE
  The potentiation of morphine or oxycodone analgesia by endothelin-A (ET(A)) receptor antagonists and imidazoline/α(2)-adrenergic agonists is well documented. However, the effect of morphine or oxycodone in combination with an ET(A) receptor antagonist or an imidazoline/α(2) adrenergic agonist on body temperature is not known. The present study was carried out to study the role of ET(A) and imidazoline/α(2) adrenergic receptors in body temperature effects of morphine, oxycodone, and clonidine in rats.
  
  
  METHODS
  Body temperature was determined in male Sprague-Dawley rats treated with morphine, oxycodone, or clonidine. Yohimbine, idazoxan, and BMS182874 were used to determine the involvement of α(2)-adrenergic, imidazoline, and ET(A) receptors, respectively.
  
  
  RESULTS
  Morphine and oxycodone produced hyperthermia which was not affected by α(2)-adrenergic antagonist yohimbine, imidazoline/α(2)-adrenergic antagonist idazoxan, or ET(A) receptor antagonist BMS182874. Clonidine alone produced hypothermia that was comparable to the hypothermia observed with clonidine plus morphine or oxycodone. The hypothermic effect of clonidine was blocked by idazoxan and yohimbine. The blockade by idazoxan was more pronounced compared to yohimbine. Clonidine hypothermia was not affected by BMS182874.
  
  
  CONCLUSIONS
  This is the first report demonstrating that ET(A) receptors do not influence morphine- and oxycodone- induced hyperthermia or clonidine-induced hypothermia. Imidazoline receptors and α(2)-adrenergic receptors are involved in clonidine-induced hypothermia, but not in morphine- and oxycodone-induced hyperthermia.
authors.affiliation: Department of Pharmaceutical Sciences, Chicago College of Pharmacy, Midwestern University, Downers Grove, IL 60515, USA. SBHALL@midwestern.edu
authors.forename: Shaifali
authors.initials: S
authors.lastname: Bhalla
authors.forename: Shridhar V
authors.initials: SV
authors.lastname: Andurkar
authors.forename: Anil
authors.initials: A
authors.lastname: Gulati
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000494:pharmacology*; D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D001833:Body Temperature Regulation / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D003000:Clonidine / Q000494:pharmacology*; D003619:Dansyl Compounds / Q000494:pharmacology; D004357:Drug Synergism; D065130:Endothelin A Receptor Antagonists; D019329:Idazoxan / Q000494:pharmacology; D054755:Imidazoline Receptors / Q000819:agonists / Q000378:metabolism*; D008297:Male; D009020:Morphine / Q000494:pharmacology; D010098:Oxycodone / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044022:Receptor, Endothelin A / Q000378:metabolism*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000701:Analgesics, Opioid; D003619:Dansyl Compounds; D065130:Endothelin A Receptor Antagonists; D054755:Imidazoline Receptors; D044022:Receptor, Endothelin A; C085754:5-(dimethylamino)-N-(3,4-dimethyl-5-isoxazolyl)-1-naphthalenesulfonamide; D015016:Yohimbine; D009020:Morphine; D010098:Oxycodone; D003000:Clonidine; D019329:Idazoxan